Michel Onfray is a fanatic. That may seem an unlikely epithet to apply to the leftist French philosopher whose Atheist Manifesto, a Number One best seller in his native country, calls for “more and more Enlightenment!” in order to debunk religion. But it fits.

The founder of a free university in Caen and a household name in France, the 48-year-old Onfray has written some 30 books, of which this is the first to be translated into English. Atheist Manifesto takes aim at the three great Western religions, making a case for atheism strictly on the basis of the alternatives’ demerits. Monotheism, Onfray argues, “seeks to promote self-hatred to the detriment of the body, to discredit the intelligence, to despise the flesh . . . it foments contempt, wickedness, the forms of intolerance that produce racism, xenophobia, colonialism, wars, social injustice. A glance at history is enough to confirm the misery and the rivers of blood shed in the name of the one God.”

To combat monotheism, Onfray writes, we must employ “sound use of our understanding, rational ordering of our minds, implementation of a true critical will.” But it quickly becomes clear that reason is not what motivates this philosopher. For example, he charges repeatedly that monotheism opposes science, citing such obvious examples as the Catholic Church’s long denial of heliocentrism. “Clearly Islam embraces astronomy, algebra, mathematics, geometry, optics,” he adds, “but only to calculate the direction of Mecca more accurately by means of the stars, to establish religious calendars, to decree prayer hours” (his italics). But why should the scientist’s motives for research—religious or not—matter? What’s wrong with an astronomer who, seeking God with his telescope, discovers a star? Onfray’s argument is a Catch-22: religion is bad because it does not embrace science; but when religion does embrace science, that science doesn’t count precisely because religion has embraced it.

This logical problem illustrates something that Onfray’s persistent sarcasm batters home: his guiding principle is not science or knowledge or reason, but rather indiscriminate—and often unresearched and irrational—opposition to religion. This means, for one thing, that he never concedes the immense debt that civilization owes to various monotheist religions, which eliminated such horrifying pagan ceremonies as human sacrifice; preserved classical knowledge through the Middle Ages; created some of the world’s greatest literature, art, and architecture; and led the movement to abolish slavery, to name just a few obvious examples.

Instead, Onfray tends simply to quote a religious text that offends our modern sensibilities, cite an historical event that resembles it, and argue that the former led inescapably to the latter. This crude approach has some disturbing consequences, such as blaming Judaism—the earliest of the three Western monotheisms—for nearly every crime for which Onfray can find Old Testament analogues. So the Israelites’ conquest of Canaan was “the first genocide” (again his italics); the Hebrew God “invented total war”; the Torah “invented the ethical, ontological, and metaphysical inequality of races.” Today’s terrorists and counterterrorists, moreover, “are continuing the religious war that began with the Torah bidding the Jews to do battle with their enemies.”

Judaism is partly responsible even for the Holocaust, it seems. Though Onfray chiefly (and bizarrely) blames Hitler’s inclination for genocide on the passage in John in which Jesus scourges the moneylenders from the Temple—“Unfortunately, the metaphoric scourge permits the dialectician and the determined theoretician to legitimize the gas chambers”—he also argues that a motto stamped on German soldiers’ belt buckles, “Gott mit uns,” derives from Deuteronomy. “These words were lifted from the speech Yahweh addressed to the Jews leaving to fight their enemies, the Egyptians, to whom God held out the promise of unspecified extermination,” Onfray explains. It happens that he’s wrong about these enemies—they’re not Egyptians, but rather the various peoples residing in Canaan. More important, he’s wrong about the motto’s source. “Gott mit uns” is only a rough paraphrase of the passage in Deuteronomy, which reads, “For the Lord your God is he that goeth with you, to fight for you against your enemies, to save you.” But the phrase occurs almost exactly in Isaiah 8:10, where there is no question of extermination (“Take counsel together, and it shall come to nought; speak the word, and it shall not stand: for God is with us”). Isaiah is the much likelier source, but it would not serve Onfray’s project of tracing German atrocities to biblical antecedents.

Onfray’s textual approach, linking religious texts directly to historical violence, has two irreparable flaws. First—and this would seem an obvious point—monotheists haven’t been the only ones engaging in violence through the ages. Onfray calls the last hundred years “the fascist century”—still more italics—but he nowhere mentions the twentieth century’s other nefarious -ism, Communism, whose atheist regimes in Russia, China, Cambodia, and elsewhere slaughtered untold millions. Indeed, history has no shortage of violence, warfare, and even genocide, regardless of what religion, if any, the perpetrators have practiced. Even if all of Onfray’s links between religious texts and violence were supportable, why should we regard atheist or pagan violence as preferable to monotheist violence?

The second flaw in Onfray’s approach is that it ignores how religion evolves beyond its fundamental texts. Consider the biblical lex talionis, the code of retributive justice, which in Exodus, Onfray writes, “calls on us to exchange an eye for an eye, a tooth for a tooth, but also hand for hand, foot for foot, burn for burn, wound for wound, bruise for bruise.” The later rabbis who interpreted the Bible regarded the eye-for-an-eye commandment figuratively, requiring someone who accidentally blinded an acquaintance not to surrender his own eye, but rather to make monetary restitution to the victim. Even the People of the Book do not follow their text literally, uniformly, and without change; their customs, practices, and interpretations evolve over time. A religious text that prescribes violence doesn’t mean that its adherents will always be violent.

Onfray’s ignorance of religion runs deeper still. He claims that “No one still subscribes to such twaddle” as the existence of hell—news to millions of Americans, for starters. He argues that the Western conception of the human body is hopelessly Christian—that “Two thousand years of Christian discourse—anatomy, medicine, physiology . . . have fashioned the body we inhabit”—apparently forgetting that the single greatest influence on medicine, during those 2,000 years, was the second-century physician Galen, who was no Christian. He oddly singles out Chabad-Lubavitch, a Hasidic sect that embraces technology wholeheartedly, as having an “ignorance of the passage of time”—of “space conquest, worldwide information networks, the real and universal time of generalized communications.” Perhaps he should visit Lubavitch’s sophisticated website, where he could sign up for e-mail updates, read news, and purchase books and DVDs. And so on.

Onfray also calls the existence of free will one of the “three pillars (along with the death drive) of all religion.” This is incorrect, of course: a raft of Reformation theologians, most prominently Martin Luther, denied the existence of free will. The point is important to Onfray’s argument, though, since he holds that free will is a pernicious idea that our judicial systems have derived from the story of the Fall from Eden, in which God punishes Adam and Eve for actions that they freely perform. Why do we imprison child-rapists, Onfray asks indignantly, who have no more chosen to suffer pedophilia than cancer patients have chosen to harbor tumors? He doesn’t even mention the obvious answer—that pedophiles may freely choose not to act on their inclinations. This abandonment of the idea of personal responsibility is even more disturbing than Onfray’s ignorance of Protestant theology.

Perhaps most astonishingly, Onfray writes that “whether Jesus really lived or not must be reduced to the status of a mere hypothesis.” People disagree about who Jesus was and what he did, of course—but suggesting that Jesus may not have existed is simply wrong. “That Jesus existed is as sure as anything from long ago can ever be,” observes John Dominic Crossan, professor emeritus of religious studies at DePaul, former chair of the Society of Biblical Literature’s Historical Jesus Section, and author of many books about Jesus and history. “I don’t think Michel Onfray exists!” he adds laughingly.

Such ignorance would be unbecoming in anyone professing to write about religion. But it’s inexcusable in a philosopher who, calling loudly for Enlightenment, claims to take up arms against ignorance. If a fanatic is someone who endorses a notion uncritically and unreservedly, then Michel Onfray is undoubtedly a fanatic. His manifesto resembles nothing so much as those irrational, vengeful religions that he caricatures and derides.